U.S. patent application number 10/960118 was filed with the patent office on 2005-04-14 for projector and projector accessory.
This patent application is currently assigned to NEC VIEWTECHNOLOGY, Ltd.. Invention is credited to Tamura, Youichi.
Application Number | 20050078279 10/960118 |
Document ID | / |
Family ID | 34419906 |
Filed Date | 2005-04-14 |
United States Patent
Application |
20050078279 |
Kind Code |
A1 |
Tamura, Youichi |
April 14, 2005 |
Projector and projector accessory
Abstract
A projector for enlarging and projecting the display image on a
light valve onto a screen is provided with: an infrared
photodetector for photodetecting infrared light that is emitted by
an electronic pen that is manipulated on the screen and that is
provided with an infrared light emission device and ultrasonic
generator; at least two ultrasonic receivers for detecting
ultrasonic waves that are emitted by the electronic pen; means for
measuring the distance to a screen; and means for supplying
coordinate data in which the position of the electronic pen on the
screen, which has been calculated based on output of the infrared
photodetector, output of the ultrasonic generator, and output of
the means for measuring the distance to the screen, has been
normalized by the length of a side of a projected rectangular image
that has been enlarged and projected.
Inventors: |
Tamura, Youichi; (Minato-ku,
JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
NEC VIEWTECHNOLOGY, Ltd.
|
Family ID: |
34419906 |
Appl. No.: |
10/960118 |
Filed: |
October 8, 2004 |
Current U.S.
Class: |
353/42 ;
348/E17.005; 348/E5.137 |
Current CPC
Class: |
G06F 3/0433 20130101;
H04N 5/74 20130101; H04N 9/3185 20130101; H04N 17/04 20130101; G06F
3/03545 20130101 |
Class at
Publication: |
353/042 |
International
Class: |
G03B 021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 10, 2003 |
JP |
2003-352921 |
Claims
What is claimed is:
1. A projector, comprising: an infrared photodetector for
photodetecting infrared light that is emitted by an electronic pen
that is manipulated on a screen and that is provided with an
infrared light emission device and an ultrasonic generator; and at
least two ultrasonic receivers that detect ultrasonic waves that
are emitted by said electronic pen; said projector being provided
with capability for acquiring a position of said electronic pen on
said screen.
2. A projector, comprising: an infrared photodetector for
photodetecting infrared light that is emitted by an electronic pen
that is manipulated on a screen and that is provided with an
infrared light emission device and an ultrasonic generator; at
least two ultrasonic receivers that detect ultrasonic waves that
are emitted by said electronic pen; and means for measuring a
distance to said screen.
3. A projector according to claim 2, wherein said projector further
comprises: means for acquiring a position of said electronic pen on
said screen from output of said infrared photodetector, output of
said ultrasonic receivers, and output of said means for measuring
the distance to said screen.
4. A projector according to claim 3, wherein said projector further
comprises calibration means for: estimating the projector-screen
distance by using said electronic pen to indicate calibration
points that are displayed by-said projector; based on the
projector-screen distance, correcting a vertical component of
Cartesian coordinates derived by converting a distance to the
electronic pen tip; performing this correction for each calibration
point; and storing the generated coordinates as corrected
coordinates.
5. A projector that enlarges and projects a display image that is
on a light valve onto a screen, said projector comprising: an
infrared photodetector for photodetecting infrared light that is
emitted by an electronic pen that is manipulated on the screen and
that is equipped with an infrared light emission device and an
ultrasonic generator; at least two ultrasonic receivers for
detecting ultrasonic waves that are emitted by said electronic pen;
means for measuring a distance to said screen; means for supplying
coordinate data in which a position of said electronic pen on said
screen, which is calculated based on output of said infrared
photodetector, output of said ultrasonic receivers, and output of
said means for measuring the distance to said screen, has been
normalized by a length of a side of a projected rectangular image
that has been enlarged and projected; and means for: performing
calibration by: estimating the projector-screen distance by using
said electronic pen to indicate calibration points that are
displayed by the projector; based on the projector-screen distance,
correcting a vertical component of Cartesian coordinates derived by
converting a distance to the pen tip; performing this correction
for each of the calibration points; and storing the generated
coordinates as corrected coordinates; and in actual drawing, for:
generating Cartesian coordinates based on the distance to the pen
tip; using the projector-screen distance that was obtained during
calibration to correct the vertical component; and using the
corrected coordinates that were obtained during calibration to
convert Cartesian coordinates after correction to panel coordinate
system.
6. A projector according to claim 1, wherein said projector is a
mirror-projection type projector.
7. A projector according to claim 2, wherein said projector is a
mirror-projection type projector.
8. A projector according to claim 3, wherein said projector is a
mirror-projection type projector.
9. A projector according to claim 4, wherein said projector is a
mirror-projection type projector.
10. A projector according to claim 5, wherein said projector is a
mirror-projection type projector.
11. A projector accessory for a projector, said projector
accessory, comprising: an infrared photodetector for photodetecting
infrared light that is emitted by an electronic pen that is
manipulated on a screen and that is provided with an infrared light
emission device and an ultrasonic generator; and at least two
ultrasonic receivers for detecting ultrasonic waves that are
emitted by said electronic pen; said projector accessory adding to
said projector capability to acquire a position of said electronic
pen on said screen.
12. A projector accessory for a projector, said projector
accessory, comprising: an infrared photodetector for photodetecting
infrared light that is emitted by an electronic pen that is
manipulated on a screen and that is provided with an infrared light
emission device and an ultrasonic generator; at least two
ultrasonic receivers for detecting ultrasonic waves that are
emitted by said electronic pen; and means for measuring a distance
to said screen.
13. A projector accessory according to claim 12, wherein said
projector accessory further comprises: a means for acquiring a
position of said electronic pen on said screen based on output of
said infrared photodetector, output of said ultrasonic receivers,
and output of said means for measuring the distance to said
screen.
14. A projector accessory according to claim 13, said projector
accessory further comprising calibration means for: estimating the
projector-screen distance by using said electronic pen to indicate
calibration points that are displayed by said projector; based on
the projector-screen distance, correcting a vertical component of
Cartesian coordinates derived by converting a distance to the pen
tip; performing this correction for each calibration point; and
storing the generated coordinates as corrected coordinates.
15. A projector accessory according to claim 11, wherein said
projector is a mirror-projection type projector.
16. A projector accessory according to claim 12, wherein said
projector is a mirror-projection type projector.
17. A projector accessory according to claim 13, wherein said
projector is a mirror-projection type projector.
18. A projector accessory according to claim 14, wherein said
projector is a mirror-projection type projector.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a projector that has an
electronic blackboard function and to a projector accessory that
adds an electronic blackboard function to a projector.
[0003] 2. Description of the Related Art
[0004] In recent years, coordinate input devices have been
developed that combine a signal processor having two ultrasonic
receivers and one infrared light photodetector with an electronic
pen having an infrared light emitting device and an ultrasonic
generator. Such devices are a form of electronic blackboard
capability in which a signal processor is installed in, for
example, a white board, the position of an electronic pen is
obtained by measuring the distance from the electronic pen to two
ultrasonic receivers, and this position then taken into a personal
computer as coordinates.
[0005] Regarding the construction, a signal processor is installed
in the corner of a white board, the image of a personal computer is
projected by a projector onto the white board, and the position of
the projected image is read into the signal processor by using an
electronic pen to designate specific positions of the projected
image (for example, the four corners of the board). The coordinates
of the electronic pen on the board are subsequently calculated by
comparing the position of the electronic pen and the previously
memorized specific positions. These calculated coordinates are
transferred to the personal computer, whereby figures that are
drawn on the board or the movement of a mouse curser are processed
(For example, refer to Japanese Patent Laid-Open Publication No.
2002-331796 (pp. 3-5, FIG. 3)).
[0006] FIG. 1A and FIG. 1B shows a typical example of the prior
art, which is next described.
[0007] As shown in FIG. 1A, signal processor 102 that is installed
on screen 100 is provided with infrared photodetector 120,
ultrasonic receiver 121, and ultrasonic receiver 122. Infrared
light pulse 104 and ultrasonic pulse 105 ("pulse" is here used to
indicate a signal that is emitted for only an instant) are
simultaneously emitted from electronic pen 103. Using the same
principle by which the distance of lightning can be calculated from
the difference between the time the lightning is seen and the time
it is heard, signal processor 102 is able to find the distance from
electronic pen 103 to each of ultrasonic receivers 121 and 122 by
measuring the time interval from the input of infrared light pulse
104 to infrared photodetector 120 to the input of ultrasonic waves
to ultrasonic receivers 121 and 122. Ultrasonic receivers 121 and
122 are fixed to signal processor 102, and the position of
electronic pen 103 as seen from ultrasonic receivers 121 and 122
can be found based on the principle of triangulation (the position
of a specific point can be calculated if the distance from the
specific point to two different known points is known).
[0008] As shown in FIG. 1B, an image is projected onto a whiteboard
by a projector; and projected image upper left 161, projected image
upper right 162, projected image lower left 163, and projected
image lower right 164 are designated by electronic pen 103 to store
the position of projected image 106 in signal processor 102
(initialization of coordinates). When electronic pen 103 is
subsequently used within projected image 106, the position of
electronic pen 103 within the image can be calculated by comparing
electronic pen 103 with the position of projected image, whereby
the mouse curser of the personal computer can be moved and icons on
the screen can be designated. This concludes the construction of
the prior art example.
[0009] In the above-described prior-art example, however,
coordinates on a planar surface can be acquired only on a
whiteboard in which a signal processor has been installed, and
cannot be acquired on a whiteboard that lacks a signal processor.
An additional problem is the necessity for initialization of
coordinates by, for example, designating the four corner of an
image.
SUMMARY OF THE INVENTION
[0010] The present invention was realized in view of these problems
and has as its object the provision of a projector having an
electronic blackboard function and a projector accessory that adds
an electronic blackboard function to a projector, this projector
and projector accessory being able to provide a solution to the
above-described two problems by providing a projector with a signal
processor or by providing a projector with a means for acquiring
the distance from a projector to a screen.
[0011] To solve the above-described problems, the projector of the
present invention includes: an infrared photodetector for detecting
infrared light that is emitted by an electronic pen that is
manipulated on a screen and that is provided with an infrared light
emission device and an ultrasonic generator; and at least two
ultrasonic receivers that detect ultrasonic waves that are emitted
by the electronic pen; the projector being provided with the
capability of acquiring the position of the electronic pen on the
screen.
[0012] Another projector of the present invention is provided with:
an infrared photodetector for detecting infrared light that is
emitted by an electronic pen that is manipulated on a screen and
that is provided with an infrared light emission device and an
ultrasonic generator; at least two ultrasonic receivers that detect
ultrasonic waves that are generated by the electronic pen; and a
means for measuring the distance to the screen.
[0013] In addition, the above-described projector may further be
provided with a means for acquiring the position of the electronic
pen on the screen from the output of the infrared photodetector,
the output of the ultrasonic receivers, and the output of the means
for measuring the distance to the screen. In addition, the
above-described projector may be further provided with calibration
means for: estimating the projector-screen distance by using the
electronic pen to indicate calibration points that are displayed by
the projector; based on the projector-screen distance, correcting
the vertical component of Cartesian coordinates derived by
converting the distance to the pen tip; performing this correction
for each calibration point; and storing the generated coordinates
as corrected coordinates.
[0014] Another projector of the present invention is a projector
that enlarges and projects a display image on a light valve onto a
screen, this projector being provided with: an infrared
photodetector for detecting infrared light that is emitted by an
electronic pen that is manipulated on a screen and that is equipped
with an infrared light emission device and an ultrasonic generator;
at least two ultrasonic receivers for detecting ultrasonic waves
that are emitted by the electronic pen; means for measuring the
distance to the screen; means for supplying coordinate data in
which the position of the electronic pen on the screen that is
calculated based on output of the infrared photodetector, output of
the ultrasonic receivers, and output of the means for measuring the
distance to the screen has been normalized by the length of a side
of a projected rectangular image that has been enlarged and
projected; and means for performing calibration by: estimating the
projector-screen distance by using the electronic pen to indicate
calibration points that are displayed by the projector, based on
the projector-screen distance, correcting the vertical component of
Cartesian coordinates derived by converting the distance to the pen
tip, performing correction for each of the calibration points, and
storing the generated coordinates as corrected coordinates; and in
actual drawing, generating Cartesian coordinates based on the
distance to the pen tip, using the projector-screen distance that
was obtained during calibration to correct the vertical component,
and using the corrected coordinates that were obtained during
calibration to convert Cartesian coordinates after correction to a
panel coordinate system.
[0015] The above-described projector may be a mirror-projection
projector.
[0016] The projector accessory of the present invention includes:
an infrared photodetector for detecting infrared light that is
emitted by an electronic pen that is manipulated on a screen and
that is provided with an infrared light emission device and an
ultrasonic generator; and at least two ultrasonic receivers for
detecting ultrasonic waves that are emitted by the electronic pen;
and adds to the projector the capability to acquire the position of
the electronic pen on the screen.
[0017] Another projector accessory of the present invention is
provided with an infrared photodetector for detecting infrared
light that is emitted by an electronic pen that is manipulated on a
screen and that is provided with an infrared light emission device
and an ultrasonic generator; at least two ultrasonic receivers for
detecting ultrasonic waves that are generated by the electronic
pen; and means for measuring the distance to the screen.
[0018] The above-described projector accessory may be further
provided with a means for acquiring the position of the electronic
pen on the screen based on the output of the infrared
photodetector, the outputs of the ultrasonic receivers, and the
output of the means for measuring the distance to the screen.
[0019] The above-described projector accessory may be further
provided with calibration means for: estimating the
projector-screen distance by using the electronic pen to indicate
calibration points that are displayed by the projector; based on
the projector-screen distance, correcting the vertical component of
Cartesian coordinates derived by converting the distance to the pen
tip; performing this correction at each calibration point; and
storing the generated coordinates as corrected coordinates.
[0020] The above-described projector may be a mirror-projection
projector.
[0021] According to the present invention, a projector having an
electronic blackboard function and a projector accessory for
endowing a projector with an electronic blackboard function are
realized by providing a projector with a signal processor or by
providing a projector with means for acquiring the distance from
the projector to a screen, thereby allowing a solution to the two
problems in the prior-art example, these problems being the
inability to obtain coordinates on any planar surface other than a
whiteboard in which a signal processor was installed, and thus, the
inability to acquire coordinates on a whiteboard that lacked a
signal processor; and in addition, the necessity for coordinate
initialization by designating the four corners of a screen.
[0022] The above and other objects, features, and advantages of the
present invention will become apparent from the following
description with reference to the accompanying drawings, which
illustrate examples of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1A and 1B are views for explaining an electronic
blackboard of the prior art.
[0024] FIG. 2 is a view for explaining a form of utilizing the
projection system of the present invention.
[0025] FIG. 3 is a block diagram showing the configuration of the
projector of the present invention.
[0026] FIG. 4 shows the coordinate conversion process by means of
the calibration operation and an actual drawing operation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] FIG. 2 shows an embodiment of the projection system of the
present invention. This projection system is composed of screen 1,
electronic pen 3 for drawing forms on the screen, and projector 7.
Electronic pen 3 has an infrared light emission device and an
ultrasonic generator.
[0028] In addition, the compositional blocks of projector 7 are
shown in FIG. 3.
[0029] Projector 7 is made up from: signal processor 10, projection
optics 40, and CPU 30. Signal processor 10 is made up from:
infrared photodetector 70, ultrasonic receivers 71 and 72, distance
measurement means 73 for measuring the distance to the screen, and
distance calculator 50 for calculating the distance to electronic
pen 3 based on the outputs of these components.
[0030] Projection optics 40 in this case indicates a mirror
projection system for projecting a display image on a light valve
(not shown in the figure) by means of a plurality of non-spherical
mirrors. A projector of this type can realize ultra-short focusing
and features the advantages offered by using an electronic
blackboard function, i.e., the ability for the person giving a
presentation to stand in front of the screen without blocking the
projection light, thus eliminating both glare and shadows.
[0031] Distance measurement means 73 for measuring the distance to
the screen is in this case constituted by an ultrasonic sensor.
[0032] The ultrasonic sensor sends ultrasonic pulses into the air
by driving a piezoelectric curved vibrator having a oscillation
frequency of approximately 40-50 KHz by burst pulses having a fixed
cycle, and uses the same vibrator to detect reflected pulse echoes
from screen 1.
[0033] Distance measurement means 73 for measuring the distance to
the screen may be a millimeter-wave echo sounder means.
[0034] Sending a continuous millimeter wave toward the screen
causes interference with the reflected waves from the screen.
[0035] The positions of the interference peaks and troughs vary
when the oscillation frequency is swept. The distance between the
projector and screen can be detected based on the trace width of
the frequency and the interference amplitude.
[0036] Distance calculator 50 calculates the three-dimensional
coordinate distance between electronic pen 3 on the screen and
projector 7 based on distance information to the screen that was
measured by distance measurement means 73 as well as the time
differences between ultrasonic pulses 51 and 52 that are received
by ultrasonic receivers 71 and 72 and infrared light pulse 4 from
electronic pen 3 that is photodetected by infrared photodetector
70.
[0037] CPU 30 carries out a process for correcting the trapezoidal
distortion during projection in the projected image input as
necessary and supplies the resulting projected image input as
output to the light valve. At the same time, CPU 30 calculates the
position of electronic pen 3 based on the output of distance
calculator 50 and supplies this result outside the projector.
[0038] Explanation next regards the operation of the projector.
[0039] Projector 7 projects an input image onto screen 1.
[0040] The principles of the operation for acquiring the position
of electronic pen 3 are similar to those of the prior-art example
in which a signal processor was provided on a screen, but in
contrast with the prior-art example, ultrasonic receivers 71 and 72
are not on the screen surface and cannot use the principles of
triangulation in a two-dimensional area. In actuality, even if the
two distances from electronic pen 3 to ultrasonic receivers 71 and
72 are found by means of ultrasonic wave pulses 51 and 52, the
position of electronic pen 3 can be determined only as somewhere on
a circle that takes as center a portion of the line that joins the
two ultrasonic receivers 71 and 72 and that is perpendicular to the
straight line, as can be seen by position 8 of electronic pen 3 as
determined by the ultrasonic receivers.
[0041] Thus, in order to acquire the position of electronic pen 3
on the screen, the distance from ultrasonic receivers 71 and 72 to
the screen must be obtained. Once this distance is found, the
position of electronic pen 3 can be limited to intersection 9
between the screen surface and the circle described by position 8
of the electronic pen that was obtained by the ultrasonic
receivers. Although there are two points of intersection between
the surface and the circle, and electronic pen 3 may also be
located at intersection 90, in actuality, only intersection 9 need
be considered.
[0042] The position of a projected image on the screen is
calculated by CPU 30 based on the distance between projector 7 and
screen 1. Using this position as a reference, the position of
electronic pen 3 is normalized and supplied as coordinate data
output. Accordingly, the position of electronic pen 3 can be
acquired without the need for projector 7 to project an image onto
screen 1.
[0043] Calibration is realized before electronic pen 3 is used.
FIG. 4 shows the calibration operation.
[0044] In calibration, by using electronic pen 3 to indicate
calibration points that are displayed by projector 7, the
projector-screen distance is first estimated, following which the
projector-screen distance is used as a basis for correcting the
vertical component of Cartesian coordinates that are derived by
converting the distance to the pen tip. This correction is carried
out for each of the calibration points and the generated
coordinates are then stored as corrected coordinates.
[0045] In actual drawing, Cartesian coordinates are generated from
the distance to the pen point, the vertical component is corrected
using the projector-screen distance that was obtained in
calibration, and the Cartesian coordinates following correction are
then converted to a panel coordinate system using the corrected
coordinates that were obtained during calibration.
[0046] Although a case was described in the present embodiment in
which the distance to the screen was obtained by using distance
measurement means 73 that assumes that the screen size is variable,
the distance to the screen may be directly applied as input to the
projector when the projector body is installed in a fixed
position.
[0047] In addition, a case was described in which signal processor
10 is mounted in projector 7, but as one option, signal processor
10 can be also be furnished as an accessory.
[0048] Although the foregoing explanation related to a case in
which the projector was a mirror-projection type projector, the
present invention is also effective for a projector of the
lens-projection type.
[0049] While preferred embodiments of the present invention have
been described using specific terms, such description is for
illustrative purposes only, and it is to be understood that changes
and variations may be made without departing from the spirit or
scope of the following claims.
* * * * *